Open top automobiles are now being fitted increasingly with a folding hardtop instead of a convertible soft top. The folding hardtop comprises as a rule a plurality of rigid roof parts each pivotable relative to the other to retract or extend the folding hardtop. Because of the rigid roof parts the folding hardtop when extended offers the vehicle occupants almost the same comfort as a regular hardtop.
Since the roof parts are pivoted relative to each other a seal is needed which in the extended condition of the roof satisfactorily drains off any water having collected on the roof parts when retracting the roof, otherwise there would be a risk of the water gaining access to the vehicle interior when pivoting the roof parts. To achieve a satisfactory seal it may be necessary that a sealing lip of a seal, arranged between the roof parts is squashed in the extended condition of the roof, to automatically right itself to its normal condition when the roof is retracted. This restoring response is influenced by the nature of the material from which the sealing lip is made. Conventional sealing lips are usually made of an elastomeric material which although having a comparatively high elastomeric response, results in a loss of springiness with dynamic loading in the long run, to the detriment of its restoring response.
This is why it is known from prior art to strengthen a sealing lip with a bracing element for satisfactory self-righting of the sealing lip. Thus, EP 0 285 925 B2 describes a seal made of an elastomeric material featuring a sealing lip for contacting a counter surface to be sealed. Embedded in the sealing lip is a bracing element of spring steel provided with recesses which in the transverse direction of the sealing lip produce areas differing in stiffness. In other words the recesses permit defining conformance of the restoring forces so that a defined restoring materializes when the sealing lip is deflected. Disclosed in addition in DT 2 127 097 is a guide for a window pane comprising sealing lips provided with a bent strip of sheet metal made of stainless spring steel for either clamping or vulcanizing in place to the sealing lips. The strips of sheet metal serve to attain both a satisfactory seal and spring tensioning the window pane in place.
The invention is based on the object of sophisticating a weatherstrip assembly of the aforementioned kind for achieving a satisfactory sealing effect of the sealing lip with a durable restoring response.
To achieve this objective a weatherstrip assembly having the features as cited above is provided in accordance with the invention as it reads from claim 1 such that the sealing lip comprises a free end section provided with a strip-shaped tensioning element.
The weatherstrip assembly in accordance with the invention is characterized by a durable restoring response of the sealing lip. The reason for this is the springy restoring element now achieving a defined restoring force. The restoring force ensures that the sealing lip automatically rights itself from the second position to the first position as soon as the counter-force exerted by a roof part no longer exists, in thus ensuring a satisfactory seal. In addition, the tensioning element provided in the free end section of the sealing lip prevents the sealing lip from deforming to the detriment of the sealing effect exerted by the sealing lip.
Advantageous aspects of the weatherstrip assembly in accordance with the invention read from the subject matter of claims 2 to 15.
Thus, it is of advantage for good practice in fabrication to extrude the sealing section and/or the fastening section in a thermoplastic elastomer (TPE) or ethylene propylene diene monomer (EPDM). Any loss of springiness detrimenting the restoring response of the sealing lip, which might arise in the course of time because of the material, is prevented by the restoring element.
It is furthermore of advantage to connect the tensioning element materially to the end section to ensure a safe fastening. The tensioning element may be, for example, embedded in the end section when extruding the weatherstrip.
In an alternative aspect of the weatherstrip assembly in accordance with the invention the end section may comprise an opening in which the tensioning element is arranged. The tensioning element and the weatherstrip can in this case be fabricated separately and assembled as required. Separate fabrication permits an independent selection of material in thus contributing towards configuring the tensioning element in accordance with the stress involved. For this purpose it has been discovered to be of advantage to fabricate the tensioning element of metal or plastics, preferably of polyamide fibers.
Preferably, the restoring element is connected to the sealing lip positively and/or non-positively in ensuring comparatively cost-effective fabrication.
In another preferred aspect of the weatherstrip assembly in accordance with the invention the sealing lip comprises an outer surface facing a first component and an inner surface opposite the outer surface, the restoring element being secured to the inner surface. Such a configuration is associated with the advantage that when the sealing lip is tensioned by the first component on the outer surface the restoring element arranged at the opposite inner surface is protected by the sealing lip.
To ensure facilitated securement of the restoring element it is of advantage when the sealing lip in the region of the inner surface comprises at least one clamping section for securing the restoring element. The clamping section permits facilitated fitting and removal of the restoring element and thus also contributes towards a design in keeping with recycling requirements.
Preferably the restoring element is made of plastics or metal, preferably spring steel to achieve a springy response by simple ways and means. In the latter case it has been discovered to be expedient to coat the restoring element in protecting it, for instance, from corrosion or other ambient effects.
In another further aspect of the weatherstrip assembly in accordance with the invention the restoring element is configured as a strip extending practically the full length of the sealing lip. Such a configuration allows for a high restoring force whilst ensuring, on the other hand, relatively simple assembly. As an alternative, a plurality of restoring elements may be arranged distributed over the length of the sealing lip. This configuration has the advantage that the restoring force exerted by the restoring elements varies over the length of the sealing lip in thus permitting conforming to the particular application in each case. For this purpose, the restoring elements may be dimensioned, for example, differingly or spaced away from each other differingly. In this case there is the advantage that because of the tensioning element arranged in the end section of the sealing lip deforming of the sealing lip detrimenting a good weatherseal is reliably prevented when the sealing lip is provided with regions of differing restoring force.
To achieve a consistent repetition of the restoring response with simple and cost-effective fabrication, the restoring element is preferably provided with an articulated bend. This articulated bend ensures that the restoring element and thus the sealing lip can be pivoted definedly from the first position into the second position and vice-versa.
In still another preferred aspect of the weatherstrip assembly in accordance with the invention the sealing section comprises an elastomeric hollow chamber which for forming a trough is arranged opposite the inner surface of the sealing lip. The trough formed between the sealing lip and the hollow chamber now makes it possible to satisfactorily drain off any water having collected on the roof parts of the folding hardtop of a motor vehicle when retracting the folding hardtop. The sealing lip and hollow chamber form in the first position of the sealing lip sufficiently high sidewalls ensuring satisfactory guidance of the water flowing through the trough in preventing the water outside of the trough from gaining access to the vehicle interior. To achieve at the same time satisfactory sealing of a component to which the weatherstrip is secured, the hollow chamber is preferably connected to a second sealing lip.